Recent developments of genetic tools for manipulating the tuberculosis bacillus make possible the construction of mutants in specific genes.
In other intracellular pathogen microorganisms such as Salmonella it has been described that the phoP gene is involved in the virulence. Inactivation of this gene has permitted the construction of attenuated mutants, which have been studied as vaccines against Salmonellosis in humans.
Our preliminary results (University of Zaragoza) in strains of the M. tuberculosis complex isolated from humans have indicated that possibly the most virulent strains have an alteration of the gene annotated in the M. tuberculosis genome as phoP.
The gene was inactivated in clinical isolation for the purpose of studying the involvement of phoP in M. tuberculosis virulence and its multiplication ability and persistence in macrophage and mouse.